Solstice Oncology raised $225 million in Series A funding to advance a next-generation CTLA-4 immunotherapy originating from Harbour BioMed. The company said it aims to move the asset into Phase 2, positioning its program to address limitations of CTLA-4 approaches in current practice. The financing supports clinical translation while keeping pressure on efficacy refinement, a key issue in immunotherapy where response rates remain uneven across tumor types. Solstice’s plan adds to the competitive landscape for CTLA-4-centered strategies, where differentiation frequently depends on pharmacology, dosing schedules and combination regimen design.